This hot chocolate is not for the faint of heart, but it's ooh so delicious. It was my mother's recipe, which I hold near and dear to my heart. Mix whole milk, cinnamon, evaporated milk and sweetened condensed milk in a large pot and bring to a slow boil, stirring constantly. Add butter and stir until completely melted. Add chocolate baking chips until completely dissolved and melted into the mixture. Turn down heat and simmer for another 5-10 minutes, or until mixture thickens.